1. Field of the Invention
The present invention pertains to capacitors of the polymer film type, with stability at high temperatures.
2. Description of the Prior Art
Prior art capacitors include capacitors based on metallized and stacked dielectric thin films. The films are made of a polymer such as polyester, polycarbonate or polypropylene. These polymers have a dielectric permittivity of about 3. It is constantly being sought to miniaturize the components and thus obtain high specific capacitances. One way of doing this is to reduce the thickness of the dielectric film as mentioned in the patent FR No. 2 548 440. According to this patent, the thin film of polymer is deposited by coating, using a solution of this polymer (the lacquer process).
Another major problem is the stability of the various characteristic parameters of a capacitor under temperature. These parameters are the value of the capacitance (namely the permittivity of the dielectric), the loss factor which must remain low and the insulation resistance which must remain high. It is difficult to find polymers possessing such qualities, all the more so as these capacitors are wanted for use at increasingly high temperatures.
To remove these disadvantages, the invention proposes to use, as a dielectric film, a polymer such as polyphenylquinoxaline or polyhydantoin. A film of this type can be obtained by casting with organic solutions or by coating (lacquering).
3. Summary of the Invention
An object of the invention, therefore, is a capacitor of the polymer film type wherein the said polymer is a polyphenylquinoxaline or a polyhydantoin.
Another object of the invention is a capacitor made up of several elementary capacitors, each elementary capacitor comprising an element of the said polymer film between a first armature and a second armature, with electrodes connecting the first armatures to each other and the second armatures to each other.